| Message ID | YerwgTIKI2PRZn3C@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] c++: ICE with noexcept and canonical types [PR101715] | expand |
On 1/21/22 12:42, Marek Polacek wrote: > On Fri, Jan 21, 2022 at 09:27:17AM -0500, Jason Merrill wrote: >> On 1/20/22 20:03, Marek Polacek wrote: >>> @@ -2815,12 +2816,23 @@ fixup_deferred_exception_variants (tree type, tree raises) >>> cp_cv_quals var_quals = TYPE_QUALS (variant); >>> cp_ref_qualifier rqual = type_memfn_rqual (variant); >>> + /* If VARIANT would become a dup (cp_check_qualified_type-wise) >>> + of an existing variant in the variant list of TYPE after its >>> + exception specification has been parsed, elide it. Otherwise, >>> + build_cp_fntype_variant could use it, leading to "canonical >>> + types differ for identical types." */ >>> tree v = TYPE_MAIN_VARIANT (type); >>> for (; v; v = TYPE_NEXT_VARIANT (v)) >>> if (TYPE_CANONICAL (v) == v >> >> I think we want to drop the TYPE_CANONICAL check here, and below change >> >> TYPE_CANONICAL (variant) = v; >> >> to >> >> TYPE_CANONICAL (variant) = TYPE_CANONICAL (v); > > OK. I couldn't really find a way to test it; clang++ rejected > my attempts with "error: exception specifications are not allowed in > typedefs" so I'm not sure if I want to add such tests even though we > happen to accept it currently. > >> so that this also works for e.g. signatures involving typedefs. >> >>> + && v != variant >> >> I think we don't need this check since we haven't changed >> TYPE_RAISES_EXCEPTIONS yet. > > And variant will never be the main variant, because of the > > if (TYPE_RAISES_EXCEPTIONS (variant) == original) > > check. Ok, so the following should be enough: > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? OK, thanks. > -- >8 -- > This is a "canonical types differ for identical types" ICE, which started > with r11-4682. It's a bit tricky to explain. Consider: > > template <typename T> struct S { > S<T> bar() noexcept(T::value); // #1 > S<T> foo() noexcept(T::value); // #2 > }; > > template <typename T> S<T> S<T>::foo() noexcept(T::value) {} // #3 > > We ICE because #3 and #2 have the same type, but their canonical types > differ: TYPE_CANONICAL (#3) == #2 but TYPE_CANONICAL (#2) == #1. > > The member functions #1 and #2 have the same type. However, since their > noexcept-specifier is deferred, when parsing them, we create a variant for > both of them, because DEFERRED_PARSE cannot be compared. In other words, > build_cp_fntype_variant's > > tree v = TYPE_MAIN_VARIANT (type); > for (; v; v = TYPE_NEXT_VARIANT (v)) > if (cp_check_qualified_type (v, type, type_quals, rqual, raises, late)) > return v; > > will *not* find an existing variant when creating a method_type for #2, so we > have to create a new one. > > But then we perform delayed parsing and call fixup_deferred_exception_variants > for #1 and #2. f_d_e_v will replace TYPE_RAISES_EXCEPTIONS with the newly > parsed noexcept-specifier. It also sets TYPE_CANONICAL (#2) to #1. Both > noexcepts turned out to be the same, so now we have two equivalent variants in > the list! I.e., > > +-----------------+ +-----------------+ +-----------------+ > | main | | #2 | | #1 | > | S S::<T379>(S*) |----->| S S::<T37c>(S*) |----->| S S::<T37a>(S*) |----->NULL > | - | | noex(T::value) | | noex(T::value) | > +-----------------+ +-----------------+ +-----------------+ > > Then we get to #3. As for #1 and #2, grokdeclarator calls build_memfn_type, > which ends up calling build_cp_fntype_variant, which will use the loop > above to look for an existing variant. The first one that matches > cp_check_qualified_type will be used, so we use #2 rather than #1, and the > TYPE_CANONICAL mismatch follows. Hopefully that makes sense. > > As for the fix, I didn't think I could rewrite the method_type #2 with #1 > because the type may have escaped via decltype. So my approach is to > elide #2 from the list, so when looking for a matching variant, we always > find #1 (#2 remains live though, which admittedly sounds sort of dodgy). > > PR c++/101715 > > gcc/cp/ChangeLog: > > * tree.c (fixup_deferred_exception_variants): Remove duplicate > variants after parsing the exception specifications. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp0x/noexcept72.C: New test. > * g++.dg/cpp0x/noexcept73.C: New test. > --- > gcc/cp/tree.cc | 22 ++++++++++++++++------ > gcc/testsuite/g++.dg/cpp0x/noexcept72.C | 21 +++++++++++++++++++++ > gcc/testsuite/g++.dg/cpp0x/noexcept73.C | 13 +++++++++++++ > 3 files changed, 50 insertions(+), 6 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept72.C > create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept73.C > > diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc > index bcd44e73921..f88006aec4f 100644 > --- a/gcc/cp/tree.cc > +++ b/gcc/cp/tree.cc > @@ -2804,8 +2804,9 @@ fixup_deferred_exception_variants (tree type, tree raises) > > /* Though sucky, this walk will process the canonical variants > first. */ > + tree prev = NULL_TREE; > for (tree variant = TYPE_MAIN_VARIANT (type); > - variant; variant = TYPE_NEXT_VARIANT (variant)) > + variant; prev = variant, variant = TYPE_NEXT_VARIANT (variant)) > if (TYPE_RAISES_EXCEPTIONS (variant) == original) > { > gcc_checking_assert (variant != TYPE_MAIN_VARIANT (type)); > @@ -2815,18 +2816,27 @@ fixup_deferred_exception_variants (tree type, tree raises) > cp_cv_quals var_quals = TYPE_QUALS (variant); > cp_ref_qualifier rqual = type_memfn_rqual (variant); > > + /* If VARIANT would become a dup (cp_check_qualified_type-wise) > + of an existing variant in the variant list of TYPE after its > + exception specification has been parsed, elide it. Otherwise, > + build_cp_fntype_variant could use it, leading to "canonical > + types differ for identical types." */ > tree v = TYPE_MAIN_VARIANT (type); > for (; v; v = TYPE_NEXT_VARIANT (v)) > - if (TYPE_CANONICAL (v) == v > - && cp_check_qualified_type (v, variant, var_quals, > - rqual, cr, false)) > - break; > + if (cp_check_qualified_type (v, variant, var_quals, > + rqual, cr, false)) > + { > + /* The main variant will not match V, so PREV will never > + be null. */ > + TYPE_NEXT_VARIANT (prev) = TYPE_NEXT_VARIANT (variant); > + break; > + } > TYPE_RAISES_EXCEPTIONS (variant) = raises; > > if (!v) > v = build_cp_fntype_variant (TYPE_CANONICAL (variant), > rqual, cr, false); > - TYPE_CANONICAL (variant) = v; > + TYPE_CANONICAL (variant) = TYPE_CANONICAL (v); > } > else > TYPE_RAISES_EXCEPTIONS (variant) = raises; > diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept72.C b/gcc/testsuite/g++.dg/cpp0x/noexcept72.C > new file mode 100644 > index 00000000000..f1455b3b46b > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept72.C > @@ -0,0 +1,21 @@ > +// PR c++/101715 > +// { dg-do compile { target c++11 } } > + > +template <typename T> struct S { > + S<T> bar() noexcept(T::value); // #1 > + S<T> foo() noexcept(T::value); // #2 > +}; > + > +template <typename T> S<T> S<T>::foo() noexcept(T::value) {} // #3 > + > +template <typename T> struct S2 { > + S2<T> bar1() noexcept(T::value); > + S2<T> bar2() noexcept(T::value); > + S2<T> bar3() noexcept(T::value); > + S2<T> bar4() noexcept(T::value); > + S2<T> bar5() noexcept(T::value); > + S2<T> baz() noexcept(T::value2); > + S2<T> foo() noexcept(T::value); > +}; > + > +template <typename T> S2<T> S2<T>::foo() noexcept(T::value) {} > diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept73.C b/gcc/testsuite/g++.dg/cpp0x/noexcept73.C > new file mode 100644 > index 00000000000..24524f3592a > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept73.C > @@ -0,0 +1,13 @@ > +// PR c++/101715 > +// { dg-do compile { target c++11 } } > + > +template <typename T> struct S { }; > + > +template<typename T> > +struct A > +{ > + A& foo(A&&) noexcept((S<T>::value)); > + A& assign(A&&) noexcept((S<T>::value)); > +}; > +template<typename T> > +A<T>& A<T>::foo(A&&) noexcept((S<T>::value)) {} > > base-commit: 45cae5b6392496028f35c5948f7fae0af81d135b
diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc index bcd44e73921..f88006aec4f 100644 --- a/gcc/cp/tree.cc +++ b/gcc/cp/tree.cc @@ -2804,8 +2804,9 @@ fixup_deferred_exception_variants (tree type, tree raises) /* Though sucky, this walk will process the canonical variants first. */ + tree prev = NULL_TREE; for (tree variant = TYPE_MAIN_VARIANT (type); - variant; variant = TYPE_NEXT_VARIANT (variant)) + variant; prev = variant, variant = TYPE_NEXT_VARIANT (variant)) if (TYPE_RAISES_EXCEPTIONS (variant) == original) { gcc_checking_assert (variant != TYPE_MAIN_VARIANT (type)); @@ -2815,18 +2816,27 @@ fixup_deferred_exception_variants (tree type, tree raises) cp_cv_quals var_quals = TYPE_QUALS (variant); cp_ref_qualifier rqual = type_memfn_rqual (variant); + /* If VARIANT would become a dup (cp_check_qualified_type-wise) + of an existing variant in the variant list of TYPE after its + exception specification has been parsed, elide it. Otherwise, + build_cp_fntype_variant could use it, leading to "canonical + types differ for identical types." */ tree v = TYPE_MAIN_VARIANT (type); for (; v; v = TYPE_NEXT_VARIANT (v)) - if (TYPE_CANONICAL (v) == v - && cp_check_qualified_type (v, variant, var_quals, - rqual, cr, false)) - break; + if (cp_check_qualified_type (v, variant, var_quals, + rqual, cr, false)) + { + /* The main variant will not match V, so PREV will never + be null. */ + TYPE_NEXT_VARIANT (prev) = TYPE_NEXT_VARIANT (variant); + break; + } TYPE_RAISES_EXCEPTIONS (variant) = raises; if (!v) v = build_cp_fntype_variant (TYPE_CANONICAL (variant), rqual, cr, false); - TYPE_CANONICAL (variant) = v; + TYPE_CANONICAL (variant) = TYPE_CANONICAL (v); } else TYPE_RAISES_EXCEPTIONS (variant) = raises; diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept72.C b/gcc/testsuite/g++.dg/cpp0x/noexcept72.C new file mode 100644 index 00000000000..f1455b3b46b --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept72.C @@ -0,0 +1,21 @@ +// PR c++/101715 +// { dg-do compile { target c++11 } } + +template <typename T> struct S { + S<T> bar() noexcept(T::value); // #1 + S<T> foo() noexcept(T::value); // #2 +}; + +template <typename T> S<T> S<T>::foo() noexcept(T::value) {} // #3 + +template <typename T> struct S2 { + S2<T> bar1() noexcept(T::value); + S2<T> bar2() noexcept(T::value); + S2<T> bar3() noexcept(T::value); + S2<T> bar4() noexcept(T::value); + S2<T> bar5() noexcept(T::value); + S2<T> baz() noexcept(T::value2); + S2<T> foo() noexcept(T::value); +}; + +template <typename T> S2<T> S2<T>::foo() noexcept(T::value) {} diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept73.C b/gcc/testsuite/g++.dg/cpp0x/noexcept73.C new file mode 100644 index 00000000000..24524f3592a --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept73.C @@ -0,0 +1,13 @@ +// PR c++/101715 +// { dg-do compile { target c++11 } } + +template <typename T> struct S { }; + +template<typename T> +struct A +{ + A& foo(A&&) noexcept((S<T>::value)); + A& assign(A&&) noexcept((S<T>::value)); +}; +template<typename T> +A<T>& A<T>::foo(A&&) noexcept((S<T>::value)) {}